1. Field of the Invention
The present invention relates to a device and a method for testing pressure loss and valve seal-tightness on a four-stroke internal combustion engine.
2. Description of the Related Art
For vehicle testing technology in repair shops, vehicle system analysis (VSA) engine testing devices or repair shop testing systems, including engine testers, are known, for example the FSA 740 edition of the applicant of the present patent application, which combine the customary functions of classical engine testers in one device. These functions include the measurement of engine-related signals such as primary and secondary ignition coils, control signals for ignition modules, rotational speed, cylinder 1 synchronization, and setting of the ignition timing. These types of VSA engine testing devices may also carry out customary checking and testing functions on recent vehicles, including reading out error memories and actual values, as well as controlling actuators, operating a signal generator for simulating sensor signals for testing sensors together with supply lines and plug-in connections, in particular in the installed state, testing components for the exact location of an error of the component in the installed state, the measuring technique and the display device being preset for the particular components. These types of engine testing devices may also be equipped with one or multiple modules for measuring vehicle emissions.
Vehicle system analysis (VSA) engine testing device 100 shown as an example in FIG. 1 is designed for use in a repair shop, in particular a motor vehicle repair shop. Engine testing device 100 is set up on a rollable stand provided with lockable rollers as shown in FIG. 1, for example, and includes a measuring unit 102, as an essential element, in which the signals are received by the various measuring sensors and converted into internally usable electrical signals, an expansion module 104 for newly added measuring functions relating in particular to the measurement of exhaust gases, a PC 106 having diskette, CD, and DVD drives as well as memory card and USB connections for external accessory devices, a display device 108, for example a monitor in particular, which is connected to the PC, input devices which are connected to PC 106, such as a keyboard 110 and a mouse 112 in particular, a printer 114, likewise connected to PC 106, for outputting measurement reports, an extendable printer cover 116 for protecting the printer and for placing tools for easy access for service personnel, a removable remote control unit 118 for remote operation of engine testing device 100, a remote control receiver 120 for receiving signals emitted by remote control unit 118, a Bluetooth USB adapter 122 and a terminal strip 130 for measuring unit 102, strip 130 being equipped with a plurality of input sockets, some of which are different, for various measuring sensors and control units, and being situated, for example, on a bottom side of measuring unit 102 (as indicated in FIG. 1) or on a back side (not shown) of engine testing device 100 situated in the rollable stand.
As mentioned above, terminal strip 130 of measuring unit 102 includes a plurality of connection sockets, some of which are different, for the various measuring sensors, for example a connection socket 132 for a temperature sensor, a connection socket 134 for the positive and negative battery terminals, a connection socket 136 for a terminal 1 measuring sensor or a terminal 15 measuring sensor, or a measuring sensor of the EFT, TN, or TD series, a connection socket 138 for a trigger device controlled by units of the ignition device of an engine to be tested, a connection socket 140 for a serial interface, for example an RS232 interface, a connection socket 142 for a sensor for measuring a negative high voltage, for example a KV− sensor, a connection socket 144 for a USB connection for a data link to the PC, a connection socket 146 for a sensor for a positive high voltage, for example a KV+ sensor, a connection socket 148 for a voltage supply of measuring unit 102 which is usable as a power supply output of measuring unit 102, a connection socket 150 for a measuring line used in many known standardized sensors, i.e., a so-called channel 1 (CH1) multimeter line or, for example, a current probe for a measuring range of up to 30 A, a connection socket 152 for a further measuring line used in various known standardized sensors, i.e., a so-called channel 2 (CH2) multimeter line or, for example, a current probe for a measuring range of up to 30 A or up to 1000 A, for example, a connection socket 154 for a stroboscope, a connection socket 156 for an air pressure sensor, and a connection socket 158 for a fluid pressure gauge. One example of a so-called clip-on trigger sensor 64 designed for use with a four-stroke internal combustion engine is shown as an example in FIG. 5.
Pressure loss testing on four-stroke internal combustion engines is presently carried out statically, i.e., with the engine idling. A static pressure loss test is relatively time-consuming, since it requires removal of various components of the engine, including the spark plugs, glow plugs, injector nozzles, etc. After the components have been removed, the piston of each individual cylinder of the engine must be brought into the so-called top dead center (TDC) of the compression stroke and fixed. A pressure loss tester is subsequently connected, acted on by compressed air, and calibrated. The pressure loss may be subsequently read off on an appropriate pressure testing device. A possible source of error, i.e., a cause of a possible pressure loss, must be ascertained by locating the air leak. It is not possible to draw conclusions concerning the seal-tightness during actual operation of the engine, i.e., with the engine running, using this type of statically conducted pressure loss testing.